Just another thought:
Turning the supply valve or tap down isn't really a solution if the
pressure is as high as you suggest.
Clamping down a valve may reduce the flow but it won't change the
pressure. When the flow stabilises, the pressure will be the same.
It's a bit like volts and amps. "Volts is pressure, Amps is flow"

Please no flames...... the OT has a pressure (volts) problem not a
flow (amps) problem so squeezing the flow won't help.

I remain curious about the pressure/head being reported in the
original post. I suspect that most providers in UK don't supply water
much above 3, 4 or 5 bar.

EP